Projector apparatuses have recently needed to have higher luminance because such projector apparatuses are used to display projected images on large-screens for, for instance, digital movie theaters or large conference rooms and further for outdoor projection mapping. Some digital movie theaters have been already about to introduce laser projectors provided with laser light source devices. Thus, a high-luminance laser light source is greatly expected. A typical single laser module can increase output within a limited range, and thus in such a high-luminance laser projector, laser beams (rays of laser light) from a plurality of laser modules are efficiently combined to increase output of light from a laser light source device.
Efforts are made to combine the laser beams from the plurality of laser modules so as to increase a spatial density of bundles of light, and also to minimize optical etendue for a light source device to have high luminance. For instance, proposed is a method for converting into smaller beam intervals than beam-emission-axis intervals of the plurality of laser modules using stepwise-arranged mirror means (e.g., Patent Documents 1 and 2).
Unfortunately, the use of the mirror means, which are stepwise arranged, the mirror means that are more remote from the laser modules are more sensitive to variations in performance due to the shapes of components and to the accuracy of their positions. As a result, a holder setting the relative positions of the laser modules and mirror means needs to be highly accurate. In addition, the mirror means need prism mirrors each having a high-accurate size, and steps of adjusting the positions of the individual mirror means or mirror-means adjustment functions with high accuracy are necessary. It is thus difficult to form an inexpensive laser light source device. Such a tendency is more noticeable in more laser modules. Thus, the stepwise-arranged mirror means are unfortunately unsuitable in an effort to further increase the output of the laser light source device. Accordingly, proposed is a method of positioning a parallel plate made of a transparent material, obliquely to a collimated bundle of light in order to increase the spatial density of the bundles of light without the use of the stepwise-arranged mirror means (e.g., see Patent Document 3).